In recent years, development of DDR4 (Double Data Rate 4) type DRAMs has been proceeding: these are DRAMs of even higher speed than DDR3 (Double Data Rate 3) type DRAMs (Dynamic Random Access Memories). DDR4 type DRAMs are provided with a new function, which is not present in DDR3 type DRAMs, namely, a CRC (Cyclic Redundancy Check) function, of detecting whether or not an error is present in write data (see Patent Reference 1).
With a CRC function, verification is performed as to whether or not an error is present in write data, by carrying out a calculation using a CRC code and write data comprising a plurality of bits. Then, if the result of the verification is that the write data contains an error, the write operation is discontinued.